Writing apparatuses and methods

ABSTRACT

Patterns are written on workpieces, such as, glass sheets and/or plastic sheets used in, for example, electronic display devices such as LCDs. The workpiece may be larger than about 1500 mm may be used. An optical writing head with a plurality of writing units may be used. The workpiece and the writing head may be moved relative to one another to provide oblique writing.

PRIORITY STATEMENT

This non-provisional U.S. patent application claims priority toprovisional U.S. patent application Ser. Nos. 60/730,009, filed on Oct.26, 2005 and 60/776,919, filed on Feb. 28, 2006, the entire contents ofboth of which are incorporated by reference.

BACKGROUND

Conventional pattern generation systems for patterning large workpiecesalso create the pattern in stripes, swaths or rectangles. The boundariesbetween them, commonly referred to as butting or stitching boundaries,create undesirable artifacts that may be visible in the final pattern.U.S. Pat. No. 5,495,279, the entire contents of which are incorporatedherein by reference, illustrates a conventional method and apparatus forexposing substrates.

Extremely high throughput, for example in the range of about 0.05 m²/sthrough about 0.2 m²/s, combined with the large size of the workpieces,(e.g., in a range of about 5 m² through 10 m², and even 20 m² or more),high optical resolution (e.g., in the range of about 3 microns throughabout 5 microns, and even down to 1 micron) and a sensitivity to “Mura”(visible striping or banding) defects creates a need to control certainerrors to 50 nm or better. Conventional pattern generators, however, areunable to do so because merely scaling up conventional patterngeneration techniques fails to achieve the required error control.

FIGS. 1D-1F illustrate example conventional pattern generators asdisclosed in U.S. Pat. No. 6,542,178, U.S. Patent Publication No.2004/0081499 and 2005/0104953, respectively, the entire contents of eachof which are incorporated herein by reference.

FIG. 1D illustrates a drum plotter as disclosed in U.S. Pat. No.6,542,178. As shown in FIG. 1D, the drum plotter includes a singlewriting unit writing optically on a rotating drum while moving along theaxis of the drum. In the drum plotter of FIG. 1D, however, only the drumholding the workpiece, but not the single writing unit, is capable ofrotating. Moreover, the drum plotter of FIG. 1D includes only a singleexposure head, and each of the drum and the single writing unit are onlycapable of a single type of movement. That is, the drum is only capableof rotating, whereas the single writing unit is only capable of lineartranslational movement.

FIG. 1E illustrates an optical system as disclosed in U.S. PatentPublication No. 2004/0081499 for thermal transfer printing on glasssubstrates for LCD production. As shown in FIG. 1E, the optical systemalso includes a single optical writing unit moving along the axis of therotating cylindrical workpiece holder. In the optical system of FIG. 1E,however, only the cylindrical workpiece, but not the single opticalwriting unit, is capable of rotating. Moreover, the optical system ofFIG. 1E includes only a single exposure head, and each of thecylindrical workpiece and the single optical writing unit are onlycapable of a single type of movement. That is, the cylindrical workpieceis only capable of rotating, whereas the single optical writing unit isonly capable of linear translational movement.

FIG. 1F illustrates a system writing optically on a rotating drum usingmultiple light sources coupled with fibers to a single writing unit andhaving the power of the light sources calibrated against a singledetector as disclosed in U.S. Patent Publication No. 2005/0104953. Asshown in FIG. 1F, the optical system also includes a single writing unitmoving along the axis of the rotating rotating drum. In the opticalsystem of FIG. 1F, as in the optical systems of FIGS. 1D and 1E, onlythe cylindrical workpiece, but not the single optical writing unit, iscapable of rotating. Moreover, the optical system of FIG. 1F includesonly a single exposure head, and each of the cylindrical workpiece andthe single optical writing unit are only capable of a single type ofmovement. That is, the cylindrical workpiece is only capable ofrotating, whereas the single optical writing unit is only capable oflinear translational movement.

The optical system of FIG. 1F further includes a photodetector fordetecting the quantity of light emitted from the single optical writingunit. This photo detector, however, only detects quantity of light fromthe single optical writing unit.

Moreover, in each of FIGS. 1D-1F, the direction of rotation is parallelwith one axis of the pattern and workpiece, while being perpendicular tothe other axis of the pattern and workpiece.

FIG. 12A shows an example alignment of movements, produced by patterngenerators such as those discussed above. Referring to FIG. 12A, threedifferent coordinate systems are present. The first is the coordinatesystem of the pattern. In this example the patterns are display devices1210, 1220, 1230 and 1240 formed on the workpiece glass. The secondcoordinate system is that of the writing mechanism 1260. In thisexample, the writing mechanism 1260 is an SLM. The third coordinatesystem is formed by the direction 1250 of movement of the writingmechanism 1260. In FIG. 12A, the three coordinate systems are alignedwith each other. Arrow 1250 indicates the rotation direction of theworkpiece relative to the pattern of the writing mechanism 1260. In theexample shown in FIG. 12A, the rotation direction is parallel to a sideof the writing mechanism (e.g., an SLM chip).

Conventional art direct write machines exposing liquid crystal display(LCD) workpieces using conventional pattern generators have write timesof about twenty-four hours (one day). In these conventional patterngenerators, writing width may be increased to reduce write time.However, this may require a larger number of optical channels and/orlenses, which may increase cost and/or complexity of the patterngenerator. The speed at which the stage is moved may also be increased.However, controlling mechanical motion and/or vibration may be moredifficult as stage speed increases. For example, an increase in speedand mass along with a decrease in application time may result in greatervibrations and/or resonances at higher frequencies in the mechanicalstructures. In addition, control and/or mechanical systems may notsettle properly before writing a new stripe. Moreover, increased speed,vibration and/or a number of optical channels may increase cost and/orcomplexity of conventional pattern generators.

SUMMARY OF THE INVENTION

Example embodiments describe mechanical, optical and/or calibrationmethods and apparatuses, which may alone or in combinationsimultaneously provide increased (e.g., high or relatively high)throughput, resolution and/or image quality on larger (e.g., large, verylarge or relatively large) workpieces.

Example embodiments relate to methods and apparatuses for patterning aworkpiece, for example, an increased throughput and/or higher precisionpattern generator for patterning multiple types of workpieces.

Example embodiments may be applied to other workpieces with similardesign and/or requirements, such as other types of displays (e.g., OLED,SED, FED, “electronic paper” and the like). The workpieces shown in theapplication are cut sheets, but may also be continuous sheets of glass,plastic, metal, ceramic, etc. Some example embodiments may also be usedto process solar panels.

Example embodiments are discussed herein with respect to standardphotolithography, for example, exposure of a resist; however, at leastsome example embodiments may also be applied to patterning by laserablation, thermal pattern transfer and/or other light-induced surfacemodification.

In at least some examples embodiments, a conventional “scan and retrace”method may be replaced by a rotating scan method, according to exampleembodiments. In addition, or alternatively, a pattern generatorincluding a rotor scanner may replace a scan and retrace patterngenerator. The rotation of the rotor scanner pattern generator,according to at least some example embodiments, may have a higherconstant speed than the scanning speed in the conventional “scan andretrace” method. A plurality (e.g., at least two) of optical writingunits may be arranged, for example, on the rim of a rotating disc orring, and may emit a beam in a radial direction.

In at least some examples embodiments, at least one of a holder forholding a workpiece and at least one writing head may be rotated. The atleast one writing head may include a plurality of exposure beams havinga wavelength for exposing a layer of electromagnetic radiation sensitivematerial covering at least a portion of a surface of a workpiece, andmay radiate in a radial direction. At least one of the holder and the atleast one writing head may be moved translationally so that the at leastone writing head and the holder move relative to each other, and form atrajectory of exposed area of the workpiece.

At least some example embodiments provide a pattern generator includinga holder adapted to hold at least one workpiece. At least one writinghead may include a plurality of exposure beams having a wavelength forexposing a layer of electromagnetic radiation sensitive materialcovering at least a portion of a surface of the at least one workpiece.At least one of the holder and the at least one writing head may beadapted to move rotationally such that the holder and the at least onewriting head move relative to one another. At least one of the holderand the at least one writing head may be adapted to move relative to oneanother such that the holder and the at least one writing head movetranslationally relative to each other such that a trajectory of exposedarea of the at least one workpiece may be formed.

In at least some examples embodiments, each optical writing unit maywrite a single pixel, an array of non-interfering pixels, or acombination thereof.

In at least some examples embodiments, one or more optical writing unitsmay include an SLM with at least between about 1000 to about 1,000,000elements, inclusive.

According to at least some example embodiments, the workpiece may befixed, and the placement of a first pattern on the workpiece may bemeasured. The written pattern may be adjusted to match a distortion ofthe first pattern. The distortion of a first pattern on the workpiecemay be measured and the distortion of said first pattern may be used tocreate a matching contiguous bitmap. The pattern written on theworkpiece may include display devices of at least two different sizes. Apattern written on the workpiece may have one display with larger areathan a quarter of the glass size.

In at least some examples embodiments, the rotating of the at least onewriting head may create a helical pattern or helical shaped trajectorieson the workpiece.

In at least some examples embodiments, the workpiece may be wrapped atleast partly around the writing head.

At least one example embodiment provides a method for generating apattern on a workpiece. The method may include scanning at least oneoptical writing unit across a surface of a workpiece creating a pixelgrid, the pixel grid being arranged at an angle relative to axes offeatures of the pattern, the angle being different from 0, 45 or 90degrees.

In at least some example embodiments, the scanning may create at leasttwo equidistant scan lines. The scanning is performed in at least twodirections.

At least one other example embodiment provides a writing apparatus forgenerating a pattern on a workpiece. The apparatus may include a writinghead including at least one optical writing unit configured to scanacross a surface of a workpiece to create a pixel grid, the pixel gridbeing arranged at an angle relative to axes of features of the pattern,the angle being different from 0, 45 or 90 degrees. The writing head maybe configured to create at least two equidistant scan lines duringscanning and/or may scan the workpiece in at least two directions.

At least one other example embodiment provides a method for generating apattern on a workpiece. The method may include rotating a rotor scannerhaving a plurality of optical writing units, each of the optical writingunits emitting electromagnetic radiation, and

scanning, concurrently with the rotating of the rotor scanner, theworkpiece by moving at least one of the workpiece and the at least onewriting head in a direction perpendicular to a plane of rotation of therotor scanner.

In at least some example embodiments, the electromagnetic radiation maybe emitted in a radial direction relative to the rotor scanner. In atleast some example embodiments, the electromagnetic radiation may beemitted in an axial direction relative to the rotor scanner. Thescanning of the workpiece may include scanning the workpiece in a firstdirection to create a pixel grid, the pixel grid being created at anangle relative to at least one of the first direction and axes of thepixel grid, the angle being different from 0, 45 and 90 degrees. Theworkpiece may be scanned in a first direction to create a helicalpattern on the workpiece. The electromagnetic radiation may be emittedin a direction parallel to at least one of a plane of rotation of therotor scanner and the scanning direction of the rotor scanner.

At least one other example embodiment provides a writing apparatus forgenerating a pattern on a workpiece. The apparatus may include a rotorscanner including a plurality of optical writing units, each of theoptical writing units emitting electromagnetic radiation. The rotorscanner may be configured to scan the workpiece by rotating the rotorscanner and moving at least one of the workpiece and the at least onewriting head in a direction perpendicular to a plane of rotation of therotor scanner.

At least one other example embodiment provides a method for patterning aworkpiece. The method may include scanning a plurality of opticalwriting units across a surface of the workpiece, each of the pluralityof optical writing units having a separate final lens, and moving theworkpiece and the plurality of optical writing units relative to eachother, the relative motion being a combination of linear movement andcircular motion in a direction perpendicular to the linear motion.

At least one other example embodiment provides an apparatus forpatterning a workpiece. The apparatus may include at least two opticalwriting units for patterning the workpiece, the at least two opticalwriting units including separate final lenses and a calibration sensorconfigured to detect characteristics of the at least two optical writingunits. The calibration sensor may detect the characteristics of theoptical writing units by scanning the at least two optical writing unitsacross the calibration sensor.

In at least some example embodiments, the apparatus may further includeat least one control unit for adjusting at least one parameter valueassociated with at least one optical writing unit based on the detectedcharacteristics.

In at least some example embodiments, the at least one control unit maycompare at least one detected characteristic to at least one setparameter value and adjusts at least one current parameter value basedon the comparison. The at least one parameter may be a focus, positionor power of an optical writing unit. The calibration sensor may includeat least two detectors, each of the at least two detectors detecting oneof the detected characteristics.

The at least two writing units may be single-point writing units,multi-point writing units or spatial light modulators. The apparatus maybe a cylindrical pattern generator.

At least one other example embodiment provides an apparatus including acylindrical holder for holding at least one workpiece, and a rotorscanner for patterning the at least one workpiece. The at least onerotor scanner may include at least two writing units and may beconfigured to move in an axial direction relative to the cylindricalholder and configured to rotate on an axis. The axis of rotation may besubstantially perpendicular to the axial movement of the cylindricalholder.

In at least some example embodiments, the cylindrical holder may holdthe at least one workpiece so as to at least partially enclose the rotorscanner, and the at least one rotor scanner may create a helical patternon the at least one workpiece by emitting electromagnetic radiation inan outward radial direction.

In at least some example embodiments, the rotor scanner may bering-shaped and configured to create a helical pattern on the at leastone workpiece by emitting electromagnetic radiation in an inward radialdirection. The cylindrical holder may further include air bearings forsupporting the ring-shaped rotor scanner. In at least some exampleembodiments, the cylindrical holder may be stationary. The at least twowriting units may be arranged in at least one row on an outer portion oran inner portion of the cylinder. Each of the at least two opticalwriting units may emit electromagnetic radiation in a different radialdirection.

At least one other example embodiment provides a writing apparatus forpatterning a workpiece. The writing apparatus may include a writing headincluding a plurality of writing units, each writing unit configured toemit electromagnetic radiation for patterning the workpiece, a detectorfor detecting characteristics of a writing unit and a control unit foradjusting the writing head to compensate for errors determined based onthe detected characteristics.

In at least some example embodiments, the control unit may be furtherconfigured to determine at least one correlation associated with atleast one of the optical writing units based on the detectedcharacteristics and adjust the writing head based on the at least onecorrelation. The control unit may determine the correlation based on acomparison of the at least one characteristic and a corresponding setparameter value.

Another example embodiment provides a method for calibrating an opticalwriting head. The method may include detecting at least onecharacteristic of an optical writing unit included in the writing head,determining a correlation between the at least one detectedcharacteristic and a corresponding set parameter value, and adjustingthe writing head based on the determined correlation. The correlationmay be generated by comparing the at least one detected characteristicwith the corresponding set parameter value. The correlation may be adifference between the at least one detected characteristic and acorresponding set parameter value. The detected characteristic may beone of a focus of electromagnetic radiation emitted from the opticalwriting unit, power of electromagnetic radiation emitted from theoptical writing unit and position of the optical writing unit.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will be more clearly understood from the followingdetailed description taken in conjunction with the accompanying drawingsin which:

FIG. 1A illustrates a rotor scanner with a single ring of single-pointwriting units, according to an example embodiment;

FIG. 1B illustrates a simplified view of the single-ring, single-pointscanner writing sequentially lines from edge to edge of the workpieceand the adjustments needed for each writing unit, according to anexample embodiment;

FIG. 1C shows an example embodiment of the rotor scanner using spatiallight modulators (SLMs) building the image from SLM fields (“stamps”)and the adjustments needed for each writing unit, according to anexample embodiment;

FIGS. 1D-1F illustrate conventional pattern generators;

FIG. 2 illustrates a writing apparatus, according to another exampleembodiment;

FIG. 3 illustrates an arrangement of calibration sensors betweenworkpieces, according to an example embodiment;

FIG. 4 is a side-view of a calibration sensor, according to an exampleembodiment;

FIG. 5 is a schematic representation of a calibration sensor, accordingto an example embodiment;

FIG. 6 illustrates a-combination optical writing unit and opticalmeasurement unit, according to an example embodiment;

FIGS. 7A-7C illustrate different implementations and orientations of adisc-type writing apparatus, according to example embodiments;

FIGS. 8A-8C illustrate different implementations and orientations of aring-type writing apparatus, according to another example embodiment;

FIG. 9 illustrates a horizontal oriented cylindrical stage or holder,according to an example embodiment;

FIG. 10 illustrates a flat workpiece, which may be written using awriting apparatus, according to one or more example embodiments;

FIGS. 11A-11K illustrate a plurality of different positions of a writinghead in relation to the direction of a rotor scanner relative to theworkpiece, according to at least one example embodiment;

FIGS. 12A-12E illustrate an SLM arrangement and workpiece arrangementrelative to the rotational direction of the rotor scanner;

FIG. 13 illustrates an auto focus arrangement, according to an exampleembodiment;

FIG. 14 is a top-view of a calibration sensor, according to an exampleembodiment;

FIG. 15 is a perspective view of a writing apparatus, according toanother example embodiment;

FIG. 16 illustrates a writing apparatus, according to another exampleembodiment;

FIG. 17 is a top view of the writing apparatus 1520 shown in FIG. 15;

FIG. 18 illustrates a writing apparatus, according to another exampleembodiment;

FIG. 19A is a side view of a writing apparatus, according to anotherexample embodiment;

FIG. 19B is a top view of the writing apparatus shown in FIG. 19A;

FIG. 20 illustrates a method for transformation of a Cartesian grid intoa bent coordinate system, according to an example embodiment;

FIG. 21 shows a vacuum arrangement for holding the workpiece on thecylinder;

FIG. 22 illustrates a writing apparatus, according to another exampleembodiment;

FIG. 23 is a more detailed illustration of the pattern generator shownin FIG. 16;

FIGS. 24A-E illustrate methods for continuous scanning in the x and ydirections, according to an example embodiment;

FIGS. 25-28 illustrate flatbed platforms, according to exampleembodiments; and

FIG. 29 shows a diagram over the position of the stage and the countermasses during scanning;

FIG. 30 illustrates a calibration system, according to another exampleembodiment; and

FIG. 31 illustrates a calibration method, according to an exampleembodiment.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Example embodiments are described with reference to the figures. Theseexample embodiments are described to illustrate the present invention,not to limit its scope, which is defined by the claims. Those ofordinary skill in the art will recognize a variety of equivalentvariations on example embodiments described as follows.

In at least some examples embodiments, a rotor scanner may be in theform of a ring. In this example, each of a plurality of optical writingunits may be arranged and configured to emit electromagnetic radiationin the form of at least one laser beam. The laser beams may be emittedin at least two directions. In at least some examples embodiments, thelaser beams may be emitted in at least two parallel directions. In atleast some examples embodiments, the laser beams may be emitted in aradial direction inward toward a workpiece arranged on a cylindricalholder positioned inside the ring-shaped rotor scanner.

In at least some examples embodiments, the rotor scanner may be in theform of a disc. In this example, each of the plurality of opticalwriting units may be arranged and configured to emit electromagneticradiation in the form of at least one laser beam in a radial directionoutward toward at least one workpiece arranged so as to at least partlyenclose the disc-shaped rotor scanner. Alternatively, the disc-shapedrotor scanner may be ring-shaped.

For the sake of clarity, a rotor scanner including optical writing unitsarranged and configured to emit electromagnetic radiation in the form ofat least one laser beam in an outward radial direction will be referredto hereinafter as a disc rotor scanner, whereas the rotor scannerincluding optical writing units arranged and configured to emitelectromagnetic radiation in the form of at least one laser beam in aninward radial direction will be referred to herein as the ring rotorscanner. A rotor scanner configured to emit electromagnetic radiation inthe form of at least one laser beam in an axial direction will bereferred to herein as an axial rotor scanner. Hereinafter, whendiscussing aspects of example embodiments applicable to both the discrotor scanner and the ring rotor scanner, the disc rotor scanner and thering rotor scanner will be referred to collectively as a rotor scanner.

The workpiece may be flexible (e.g., very flexible) and may need acylindrical support to have and maintain a desired radius. The innerpart of the workpiece may more easily assume a cylindrical shape;however, at edges parallel to the cylinder axis, a bending moment may beintroduced to start bending the workpiece at the proper bending radius.This bending moment may be on the order of a few kg*cm, and may beintroduced by a lengthwise clamp. This clamp may also support theworkpiece as workpiece is loaded into the machine.

The workpiece may have a thickness tolerance of about +/−70 μm and avariation of less than about 20 μm over a length of about 150 mm. Thisvariation may disturb the focus position and may be corrected in focusand/or in the shape of the workpiece. For example, the shape from therotor scanner may be measured, and the shape of the workpiece may becorrected. The active workpiece shape may be corrected only within thewriting zone. In this example, the corrector hardware may follow alongwith the rotor scanner assembly, which may reduce the number ofactuators. The use of a corrector may use optics with a shorter depth offield.

The rotor scanner may be supported by bearing pads (e.g., air bearingpads) that may control the position of the axis of rotation and/or thelengthwise position of the rotor scanner. The positioning in thedirection of rotation may be adjusted by timing of the pattern. Thedynamic positioning in the axis lengthwise direction may, depending onthe design, need active components to move the image plane.

The rotor scanner position may be determined by several differentmethods, according to example embodiments. For example, in the ringrotor scanner marks on the periphery may be detected, for example,optically, and the position of the rotor scanner may be interpolatedbetween these marks or positions. The air friction may be reduced (e.g.,to about 0.1 N), and the speed may be increased. The time betweenmarkers may be shorter and/or the possible deviations due to residualforces may decrease as this “time between markers” squared. In exampleembodiments having a vertical axis, internal accelerometers in the rotorscanner may be mused to achieve a more accurate feedback signal. Thefeedback signal may be used for velocity control. In example embodimentshaving a horizontal axis, accelerometers may also be used; however, inthis case the accelerometers may need to be balanced such that thedirection of the forces of gravity is unseen. Although not describedherein, interferometry or any other suitable methods may also be used.

Velocity differences of the scanner rotor may be measured with, forexample, internal rotation accelerometers and the rotational accuracymay be improved. Angular position of the rotor scanner may be measuredusing a plurality of markers (e.g., optical markers) around an outeredge of the rotor scanner. A control system may use the markers as anabsolute measurement of position of the rotor, and may interpolate the“in between position” by time. The accuracy of the interpolation may beincreased by using internal rotational accelerometers.

The rotor may be balanced using distance sensors, a pressure signal froma bearing pad, or any other suitable measuring device. In exampleembodiments, the rotor scanner may be supported by bearings, airbearings, air bearing pads, etc.

In at least some examples, transfer of data may be eased by renderingthe patterns such that they are streamed to the rotor with littleadjustment. In this example, the data may be rendered in a predistortedmanner, and stored so that each arc is represented by a column of datain the memory. As the workpiece is written, columns may be read (e.g.,successively) from left to right in a memory matrix and the data may besent through to the rotor scanner.

FIG. 1A shows a rotor scanner with a single ring of single-point opticalwriting units, according to an example embodiment. FIG. 1B shows asimplified view of the single-ring, single-point scanner writingsequentially lines from edge to edge of the workpiece, and theadjustments needed for each writing unit. FIG. 1C shows an exampleembodiment of a rotor scanner using SLMs to generate the image from SLMfields (“stamps”) and the adjustments needed for each writing unit.

Referring to FIG. 1A, the pattern generation apparatus may include arotor scanner 1. The rotor scanner 1 may be disc shaped and may includeat least one (e.g., a plurality of) writing head 10. Each of the writeheads 10 may emit light in a radial direction. A workpiece 20 may partlyenclose the rotor scanner 1. The rotor scanner 1 may be rotatable andmay rotate at a constant or substantially constant speed. A power slipring may be placed at the center. The slip ring may be a graphite/copperslip ring, an HF transformer contactless slip ring, a frictionless slipring, or any other suitable slip ring. In example embodiments, an HFslip ring may reduce (e.g., eliminate) dust common with ordinary sliprings.

Still referring to FIG. 1A, a workpiece may be bent such that thecurvature of the workpiece has a radius larger (e.g., slightly larger)than that of the disc rotor scanner and/or such that the focal spot ofthe optical system may be matched. Alternatively, in example embodimentsof the ring rotor scanner, a workpiece may be bent such that thecurvature of the workpiece has a radius less than that of the ring rotorscanner and/or such that the focal spot of the optical system may bematched. In example embodiments in which the workpiece is bent orcurved, the workpiece may be, for example, a workpiece capable ofbending to a desired curvature, such as, a glass workpiece, a plasticworkpiece, etc.

In an example embodiment in which a workpiece is bent (e.g., wrapped) toa curvature spanning about 180°, the disc rotor scanner may have adiameter of, for example, about 1.4 meters (m). A smaller bend radius(e.g., a minimum bend radius) of about 1.3 m may be used when theworkpiece is wrapped about 180 degrees around a disc write head. Thecylindrical support for a glass wrapped approximately 180 degrees mayhave a radius of between about 1 and about 2 meters, inclusive.

In a system for writing one workpiece at a time the workpiece may bebent to about or near 360°. A workpiece (e.g. glass, plastic, metal,ceramic, etc.) may be between about 2 and about 3 meters, inclusive, orup to about 6 meters and the corresponding cylinder for a single glassmay have a radius of about 0.35 to about 0.6 meters, inclusive, and upto about 1 meter. Bending a glass workpiece with a radius of about 1.3meters may produce a stress of around 31 MPa per mm workpiece thickness.With workpiece thickness of about 0.7 mm the stress may be about 22 MPa,and only a smaller fraction of the safe stress.

In another example, if the workpiece is wrapped to a curvature spanningabout 120°, the disc rotor scanner may have a diameter of about 2.1 m.In this case it may be suitable to employ a cylindrical support with aradius of about 2 to about 3 m, inclusive. In these examples, theoverall width of the pattern generator may be smaller than that ofconventional pattern generators and/or writing apparatuses, for example,about 2 m wide. The workpiece may be sectional (e.g., cut into sheets)or in a continuous form, for example, for roll-to-roll processing ofdisplays and/or solar panels.

Referring back to FIG. 1A, the rotor scanner may rotate in acounter-clockwise direction; however, alternatively the rotor scannermay rotate in a clockwise direction. As shown in FIG. 1A, whilerotating, the rotor scanner 1 may be moved in an upward vertical scandirection 50; however, it will be understood that the rotor scanner maymove in a downward direction or a horizontal direction (e.g., to theright or to the left). A pattern to be printed on the workpiece 20 maybe determined by a modulation of the writing heads 10. During operation(e.g., patterning or writing), electromagnetic radiation from thewriting heads 10 may form a helical pattern 30 on the workpiece 20.

The lengthwise scan of the workpiece 20 may be accomplished by movingthe workpiece 20 and/or the rotor scanner 1. Because the rotor scanner 1may be thinner or substantially thinner than the workpiece 20 and/orworkpiece holder (not shown), the rotor scanner 1 may be moved and theworkpiece 20 may be written without a need for additional length. Thenon-rotating part of the rotor scanner 1, or bearing pads may performthe axial scan and/or carry other (e.g., all other) functions.

A rotor scanner 1 may be supported by bearing pads (e.g., air bearingpads). In this example, the ring design may have additional room for thebearing pads on the inner ring radius.

The rotor scanner 1 may be balanced (e.g., very accurately balanced).Any residual unbalance may be more easily detected, for example, byback-pressure variations in the bearing pressure pads (e.g., air bearingpressure pads) or by other position sensors. An automatic balancingsystem that may continuously balance the rotor scanner may also be used.Disturbances to the rotor scanner 1 may be a result of airflow betweenthe rotor scanner and/or a rotor scanner shield. If the air flow betweenthe rotor scanner and the rotor scanner shield is forced to be laminar,for example, by choosing a suitably small gap (e.g., a few mm at 5 m/s),stability of the operating conditions may be increased. The laminar flowmay introduce forces, for example, stationary forces. In exampleembodiments, the power loss to friction may be reduced (e.g., to a fewwatts), and the rotor scanner may be driven by any suitable motor. Forexample, the friction at a 1 mm gap at 5 m/s may have a loss of 0.5 Wper m². The bearing pads may have a smaller gap and/or larger drag,which may be offset by the smaller area. The motor may have a drivesystem having uniform, or substantially uniform, torque while turning.

The number of optical writing units included in the disc rotor scanner 1may be based on write speed. In at least one example embodiment, thewriting units may be fed data from a data channel with a higher (e.g., avery high) data rate, (e.g., about 200, 400, 500 or more Gbit/sec).Because the machine may be used for production, the pattern may be thesame or substantially the same at all times. If the pattern is storedlocally inside the rotor scanner, the pattern may be loaded at a lowerspeed (e.g., through a conventional high speed link) while the rotorscanner is stationary. The pattern may then reside (e.g., permanentlyreside) in memory. This may avoid the rotating data joint.

As shown in FIGS. 1A and 1B, the optical writing units may be, forexample, single point laser diodes. The laser diodes may be of anycommercial available wavelength such as blue, red, violet, etc. Thepower of a laser diode may be, for example, about 5 mW to about 65 mW,inclusive for single mode, and about 5 mW to about 300 mW, inclusive formultimode diodes. An electro-optical efficiency of a laser diode may be,for example, about 13%. The laser diodes may act as an optical powersource and a modulator, for example, simultaneously. Alternatively, asshown in FIG. 1C, the optical writing units may be SLMs.

The axis of rotation of the rotor scanner may be vertical, horizontal,or any angle there between. The vertical axis arrangement may have aconstant, or substantially constant, acceleration of the optical writingunits at all times. The horizontal axis arrangement may handle theworkpiece more efficiently and/or with less effort absent the need tocounteract forces of gravity.

FIGS. 7A-7C illustrate different implementations and orientations of awriting apparatus, according to example embodiments. The disc rotorscanner discussed below with regard to FIGS. 7A-7C may be the same orsubstantially the same as the disc rotor scanner 1 of FIG. 1. Therefore,a detailed discussion will be omitted for the sake of brevity.

Referring to FIG. 7A, the writing apparatus 700 may include a holder(e.g., a tubular holder) 710, a disc rotor scanner 730 and/or at leastone optical writing unit 740. In at least some examples embodiments, thedisc rotor scanner 730 may include a plurality of optical writing units740.

The workpiece 720 may be arranged inside the workpiece holder 710. Acentral axis of the formed holder 710 may be arranged, for example,horizontally. The holder 710 may be kept at a fixed position, while thedisc rotor scanner 730 rotates and/or moves in a direction parallel orsubstantially parallel to the central axis. The optical writing units740 may be arranged on an outer edge of the disc rotor scanner in atleast one row, but are shown as including two rows in FIG. 7A. Theoptical writing units 740 may face an inner surface of the workpieceholder 710. Alternatively a single row or greater than two rows ofoptical writing units 740 may be used.

Referring to FIG. 7B, the central axis of the workpiece holder 710 maybe arranged vertically. The workpiece 720 may be arranged inside theholder 710 as discussed above with regard to FIG. 7A. The workpiece 720may be fixed in the holder 710 by forces, which may flatten, orsubstantially flatten the workpiece 720. Alternatively, the workpiece720 may be fixed to the holder 710 by vacuum nozzles. In this example,the workpiece 720 may be fixed in the holder 710 by removing the airbetween the workpiece 720 and the holder 710. The workpiece 720 andholder 710 may be fixed while the disc rotor scanner 730 may rotateand/or move vertically (e.g., upward and/or downward).

Referring to FIG. 7C, the writing apparatus of FIG. 7C may be similar orsubstantially similar to the writing apparatus discussed above withregard to FIG. 7B. However, in the writing apparatus of FIG. 7C, theworkpiece 720 and/or the holder 710 may rotate while the disc rotorscanner 730 moves in a vertical direction (e.g., upwards and/ordownwards).

FIG. 2 illustrates a writing apparatus, according to yet another exampleembodiment. As shown, the writing apparatus of FIG. 2 may be used topattern a plurality of workpieces concurrently or simultaneously.Although the writing apparatus of FIG. 2 will be discussed with respectto patterning three workpieces 222A, 222B and 222C, simultaneously, itwill be understood that any number of workpieces may be patternedconcurrently. The rotor scanner 220 of FIG. 2 may be the same orsubstantially the same as the rotor scanner 1 of FIG. 1.

Referring to FIG. 2, the workpieces 222A, 222B and 222C, may at leastpartially enclose or surround the rotor scanner 220. As shown, openings224, 226, and 228 may be left between each of the workpieces 222A, 222Band 222C. At least one of a detector and a calibration sensor (notshown, but described in more detail below) may be positioned in eachspace between the workpieces. In at least one example embodiment, thedetector and/or calibration sensor may monitor the position, focusand/or power of the rotor scanner 220. Any misalignment of the rotorscanner 220 relative to a desired position may be compensated, forexample, using dose, modulation delaying, timing, image distortion, orany other suitable manner.

FIG. 3 illustrates a plurality of calibration sensors 310, 320 and 330positioned in the openings 224, 226 and 228, respectively. As shown inFIG. 3, three workpieces are held by the writing apparatuses and threecalibration sensors are used. In accordance with example embodiments,the number of calibration sensors may be correlated to the number ofworkpieces concurrently arranged in the writing apparatus. In someexample embodiments, the number of calibration sensors may be equal tothe number of workpieces.

FIG. 4 is a top view of a portion of the writing apparatus of FIG. 2including a calibration sensor (e.g., a calibration eye), according toan example embodiment. FIG. 14 is a side view corresponding to the topview of FIG. 4.

Referring to FIGS. 4 and 14, the calibration sensor 400 may detectposition, power and/or may focus individual beams 410 of a rotor scanner430 based on characteristics of the electromagnetic radiation emittedfrom the optical writing units (not shown) of the rotor scanner 430. Inat least some example embodiments, the calibration sensor 400 mayinclude an interferometer (not shown) for measuring the position (e.g.,the vertical position of the rotor scanner if the pattern generationapparatus is oriented vertically) of the rotor scanner 430.Interferometers are well-known in the art, and therefore, a detaileddiscussion will be omitted for the sake of brevity. The rotor scanner430 may be the same or substantially the same as the rotor scanners 1and/or 220, and thus, a detailed discussion will be omitted for the sakeof brevity.

If a single workpiece 420 is wrapped on the holder, the calibrationsensor 410 may be arranged between the edges of the workpiece 420. Inexample embodiments, the workpiece 420 may be wrapped onto a holder(e.g., a tubular shaped holder). The rotor scanner 430 may rotate insidethe wrapped workpiece 420. In at least example embodiments, a distancebetween a scanner base 440 and the rotor scanner 430 may be measuredusing, for example, laser interferometry or any other suitabletechnique.

FIG. 5 is a schematic representation of the calibration sensor 400,according to example embodiments. The calibration sensor 400 may includea lens assembly 510 through which electromagnetic radiation, emittedfrom the optical writing units of the rotor scanner may pass. Theelectromagnetic radiation may be partially reflected by a beam splitter520. A first portion of the electromagnetic radiation may pass throughthe beam splitter 520 and irradiate a first quadrant detector 550. Asecond portion of the electromagnetic radiation may be reflected by thebeam splitter 520, be focused by a cylindrical lens 530 and impinge afocus detector 550. The quadrant detector 550 may further include aplurality of quadrant detectors A, B, C and D, collectively referencedby 560. The focus detector 540 may include plurality of quadrantdetectors E, F, G and H, collectively referenced by 570.

In example embodiments, the quadrant detector 550 may determine aY-measure measure using the equation (A+C)−(B+D), the timing of therotor scanner using the equation (A+B)−(C+D) and the enable of the rotorscanner using the equation (A+B+C+D). The focus detector 540 maydetermine the focus of the beams emitted by the writing units using theequation (E+H)−(F+G). The focus detector 540 may be any suitable devicefor measuring de-focus using, for example, an astigmatic (on axis)optical system. The astigmatism is added using the cylindrical lens 540.The cylindrical lens 540 adds power along an axis perpendicular to theaxis of rotation of the cylinder. The axis of the cylinder may be tiltedsuch that that the cylinder passes through centers of, for example,detectors E and H.

Using the cylinder lens, an imaging system with two different powers maybe realized. In one direction (D1), where the cylinder adds its power,and another direction (D2), where it does not.

When the focus position matches the power of D1, a line image passingthrough the center of detectors E and H (e.g., along the axis of thecylinder) is produced. Conversely, if the focus point position matchesthe power of D2, line image is produced along the center of detectors Fand G. Thus, the difference (E+H)−(F+G) is proportional to a position ofthe focal point.

The calibration sensor of FIG. 5 may be used to calibrate focus, powerand/or position of the optical writing units. For example, the focusdetector 540 and the position detector 550 in FIG. 5 may be used tocalibrate a focus and position detector in each optical writing unit. Afocus and position detector and each optical writing unit will bedescribed in more detail with regard to FIG. 6 below.

FIG. 6 illustrates an optical writing unit (e.g., a writing laserdiode), according to an example embodiment. The optical writing unit 600of FIG. 6 may be used as the optical writing units 740 of FIGS. 7A-7Cand/or the optical writing units 840 of FIGS. 8A-8C.

Referring to FIG. 6, the optical writing unit 600 may include adigital-to-analog converter (DAC, e.g., a high speed DAC) 610 fortransforming pattern data into modulation signals for the blue laserdiode 660. The pattern data may be received via a data channel (notshown). The data channel may be, for example, a fiber-optic cable, aradio-frequency (RF) link passing through the center of the HFtransformer, or any other suitable data channel capable of providinghigher data rates, such as, 200 Gbits/s, 400 Gbits/s, 500 Gbits/s, etc.

The modulation signals generated by the DAC 610 may be output to a powercontroller 620. The power controller 620 may control the power of a bluelaser 660 based on the modulation signals from the DAC 610 and powercontrol signals output by a power detector 630. The blue laser 660 mayemit electromagnetic radiation (e.g., blue laser beam) for patterningthe workpiece 665 based on power control signals output from the powercontroller 620. The blue laser output from the blue laser 660 may passthrough a lens assembly 670, which may make the beam telecentric. Afterpassing through the lens assembly 670, the telecentric blue laser may beincident on a beam splitter 680. The beam splitter 680 may direct aportion (e.g., a relatively small portion) toward the lens assembly 650.The remaining portion of the blue laser beam may pass through the beamsplitter 680 and be focused on the workpiece by the focus lens assembly690.

The redirected portion of the blue laser beam may be focused by the lensassembly 650, pass through red block 640 and be incident on the powerdetector 630. The power detector 630 may detect the power of theincident blue laser light, and output a power control signal indicativeof the detected laser power. The red block 640 may block (e.g., reflect,absorb, etc.) all, or substantially all, red laser light incidentthereon.

A red laser diode 655 may also emit electromagnetic radiation in theform of red laser beam. The red laser beam may be used for positioning,focus control and/or determining shape of the workpiece. In at least oneexample embodiment, the red laser beam may pass through a telecentriclens assembly 645 and be incident on a beam splitter 615. Thetelecentric lens assembly 645 may be the same or substantially the sameas the telecentric lens assembly 670 discussed above. Thus, for the sakeof brevity, a detailed discussion will be omitted. A beam splitter 615may transmit the red laser beam to the beam splitter 680, which maydirect the red laser beam onto the workpiece 665. The red laser beam maybe reflected by the workpiece 665 back toward the beam splitter 680,which may relay the red laser beam toward the beam splitter 615. Thebeam splitter 615 may direct the red laser light toward the focus andposition detector 685 via cylindrical lens 635 and/or blue laser block625. The blue laser block 625 may block (e.g., reflect, absorb, etc.)all, or substantially all, blue laser light incident thereon.

The focus and position detector 685 may output positioning signals to afocus Z servo 675. The focus Z servo 675 may receive the positioningsignals from the position detector 685 and calibration data, and controlthe position of the lens assembly 690 via a data connection (e.g., a 1kHz bandwidth data line). For example, the focus Z servo 675 may movethe lens assembly 690 in an X-direction, Y-direction and/or Z-directiondepending on the shape of the signal from the focus and positiondetector 685. The control loop signals may be supplemented by feedforward signals from a control system (e.g., a computer or processor,not shown) to correct for known distortions such as focus errors.

According to at least some example embodiments, a position and/or formof the workpiece may be determined using laser diodes having awavelength not affecting the electromagnetic radiation sensitive layeron top of the workpiece. In at least some examples, blue laser diodesmay affect the electromagnetic radiation sensitive layer and red laserdiodes may be used for measurement of the position and form of theworkpiece. Laser diodes exposing the workpiece and laser diodes used formeasurement and not affecting the electromagnetic radiation sensitivelayer may be arranged in the writing head (rotor).

FIG. 13 is a more detailed illustration of an auto focus arrangement ofan optical writing unit for focusing and position (or displacement)determination, according to an example embodiment. Emittedelectromagnetic radiation (e.g., a laser beam) from a laser diode 1310enters a lens assembly 1330, which telecentrizes the beam. Thetelecentric beam may impinge on a beam splitter 1340, which directs thebeam toward a lens assembly 1350. The lens assembly 1350 may focus thebeam onto the workpiece 1370. A cover glass 1360 may be arranged betweenthe lens assembly 1350 and the workpiece 1370 to protect the lensassembly 1350. When the beam impinges on the workpiece 1370, the beammay be reflected back through the lens assembly 1350 to the beamsplitter 1340. The beam splitter 1340 may direct the reflected beam ontothe detector 1320 for detecting the focus of the laser beam. Thedetector 1320 may detect the focus of the laser beam in any suitablewell-known manner. Because methods for detecting focus of a laser arewell-known in the art, a detailed discussion will be omitted for thesake of brevity. The lens assembly 1350 may be moved in any directionbased on the read out of the detector 1320.

Referring back to FIG. 6, each optical writing unit 600 may have a setvalue for each of the power, position and focus parameters. When theoptical writing unit 600 passes the calibration sensor of FIG. 5, theoptical writing unit 600 obtains data as to how each set parameter valuecorrelates to a parameter value (e.g., power, position and/or focusvalue) measured by the calibration sensor. The error or differencebetween the set values stored in the optical writing units 600 and themeasured values is sent to the writing head for adjustment, for example,to offset the writing head's internal scale. This adjustment may bedone, for example, each time each optical writing unit passes acalibration sensor. However, the adjustment may be performed less often.

According to example embodiments, the calibration of power, focus and/orposition (x,y, where x is done by time delay) may be in differentcalibration sensors, so long as the calibration source of each focus,power and position is common. That is, for example, power, focus and/orposition may be calibrated using a different calibration sensor so longas each writing head uses the same calibration sensor for focus, thesame calibration sensor for power, and the same calibration sensor for xposition and the same calibration sensor for y-position. Power may bemeasured in a wavelength dependent manner to compensate for variation ofwavelength sensitivity of the resist.

FIG. 30 illustrates a calibration system, according to another exampleembodiment. As shown, the calibration system may include a detector3100, a control unit 3102 and a writing head 3104. The detector 3100 maybe, for example, a calibration sensor (e.g., as discussed above withregard to FIG. 5) or any other optical detector capable of detecting,for example, focus, power and/or position of one or more optical writingunits. The control unit 3102 may be implemented, for example, in theform of software executable on a computer or processor. The writing head3104 may be a writing head including a plurality of optical writingunits, one or more of which may be an optical writing unit as describedabove with regard to FIG. 6. However, the writing head may be anywriting head capable of exposing a workpiece and/or generating a patternon a workpiece. Each of the detector 3100, the control unit 3102 and/orthe writing head 3104 may be connected via a data channel. The datachannel may be, for example, a fiber-optic cable, a radio-frequency (RF)link passing through the center of the HF transformer, or any othersuitable data channel. An example operation of the calibration system ofFIG. 30 will be described with regard to FIG. 31.

FIG. 31 illustrates a calibration method, according to an exampleembodiment. As discussed above, the method of FIG. 31 may be performed,for example, by the calibration system of FIG. 30. The method of FIG. 31may also be performed by one or more calibration sensors (e.g., 400 ofFIG. 4) in connection with one or more writing heads (e.g., 430 of FIG.4). In these examples, the control unit 3102 may correspond to, forexample, the power control unit 620 and the focus Z servo 675 of FIG. 6,and the detector 3100 may correspond to the quadrant detector 550 ofFIG. 5, the focus detector 540 of FIG. 5 and the power detector 630 ofFIG. 6. In the example embodiment shown in FIG. 30, the quadrantdetector 550 of FIG. 5, the focus detector 540 of FIG. 5 and the powerdetector 630 of FIG. 6 may be located at the detector 3100, and thepower control unit 620 and the focus Z servo 675 may be located at thecontrol unit 3102. Alternatively, however, other configurations arepossible.

Referring to FIG. 31, at S3110, when an optical writing unit of thewriting head 3104 passes the detector 3100 may detect at least onecharacteristic of the optical writing unit. For example, the detector3100 may detect characteristics, such as, focus, position and/or powerof electromagnetic radiation (e.g., the laser beam) emitted from theoptical writing unit. The detector 3100 may send the at least onedetected characteristic to the control unit 3102.

At S3112, the control unit 3102 determines a correlation between thedetected characteristics and a corresponding set parameter value. Forexample, a detected focus characteristic may be compared with a setfocus parameter value, a detected power characteristic may be comparedwith a set power value and/or a detected position characteristic may becompared with a set position value. The set parameter values may be set,for example, by a human operator, based on empirical data. In at leastone example embodiment, the correlation associated with each detectedcharacteristic and corresponding set parameter value may be an error ordifference between the set value and the measured characteristic value.The set parameter values may be stored in a memory at the control unit3102. The memory may be any suitable storage medium, such as, a flashmemory or the like.

At S3114, the control unit 3104 may adjust the writing head based on thedetermined correlation. For example, the determined correlations may beused to offset the internal scale of the writing head 3104.

Although only a single iteration of this method is shown in FIG. 31, theoperation described therein may be done, for example, each time eachoptical writing unit passes a calibration sensor. However, theadjustment may be performed less often.

FIGS. 8A-8C illustrate different implementations and orientations of aring-type writing apparatus, according to another example embodiment.

Referring to FIG. 8A, the writing apparatus may include a holder (e.g.,a cylindrical stage or tube formed holder) 810, a rotor scanner 830and/or at least one optical writing units 840. A workpiece 820 may bearranged on the outside of the holder 810. The workpiece 820 may befixed onto the holder 810 using, for example, vacuum nozzles 850. Therotor scanner 830 may rotate outside the workpiece holder 810 andoptical writing units 840 may emit radiation in a radial directioninward toward the central axis of the holder 810. In exampleembodiments, the optical writing units may be, for example, 840 may be,for example, single point laser diodes, multi-point laser diodes orspatial light modulators (SLMs). The laser diodes may be of anycommercial available wavelength such as blue, red, violet, etc. Thepower of a laser diode may be, for example, about 5 mW to about 65 mW,inclusive, for single mode, and about 5 mW to about 300 mW for multimodediodes. An electro-optical efficiency of a laser diode may be, forexample, 13%. The laser diodes may act as an optical power source and amodulator, for example, simultaneously. The spatial light modulators(SLMs) 840 may be at least partially transmissive spatial lightmodulators, and may create stamps or patterns 860 on the workpiece 820.SLMs are well-known in the art, and thus, a detailed discussion will beomitted for the sake of brevity. As shown in FIG. 8A, the central axisof the workpiece holder 810 may be oriented horizontally.

Still referring to FIG. 8A, in operation, the ring rotor scanner 830 mayrotate around the central axis of the holder 810 and move in an axialdirection relative to the holder 810 and parallel to the central axis ofthe holder 810. In addition, the holder 810 may rotate around itscentral axis in a rotational direction opposite to that of the ringrotor scanner 830.

FIG. 8B shows an example embodiment including a stationary cylindricalholder 810 holding a wrapped workpiece 820, and a rotating writing head830. Referring to FIG. 8B, the workpiece holder includes a slit 870 inwhich a calibration sensor 850 is arranged. The calibration sensor 850may be movable or fixed. The writing head 830 includes a plurality ofoptical writing units 840 creating patterns 860 on the workpiece 820. Analignment camera 880 may capture an existing pattern on the workpiece820 such that a written pattern may be aligned with higher accuracy,thereby increasing overlay precision.

FIG. 8C shows an example embodiment including a rotating cylindricalholder 810 holding a wrapped workpiece 820, and a stationary writinghead 830. The writing head 830 may include a plurality of opticalwriting units 840 creating patterns 860 on the workpiece 820. Theoptical writing units 840 of FIG. 8C may be the same or substantiallythe same as the optical writing units 840 of FIG. 8A. As is the casewith respect to FIG. 8B, the writing head 830 may include multiplewriting units 840, although, for the sake of clarity, only one writingunit 840 is illustrated.

FIG. 9 shows a horizontal orientation of a cylindrical stage or holder910, according to an example embodiment. When loaded horizontally, aworkpiece 920 may be kept in place by gravitational force. The workpiece920 may be held in place by a vacuum to ensure that the surface followsthe surface of the cylinder 910 closely. The ends of the workpiece 920may be fastened securely to the cylinder by a latch 930. The latch 930may be controlled to capture or release the edge of the workpiece 920.

The workpiece may be pushed or pulled onto or into the cylindricalsupport surface to assume the proper shape. In another example, a vacuumclamp or any other suitable clamp may also be used. The edges along thecylindrical part may bend locally away from the center or curvature(e.g., similar to bending an eraser). This bending may be restrained bya fixture system (e.g., a vacuum fixture system).

FIG. 21 shows a vacuum arrangement for holding the workpiece on thecylinder. As shown, vacuum and pressure devices may be alternatelyarranged. A push-pull vacuum clamping system may be used to counteractworkpiece deformation in the x-y plane. As shown in FIG. 21, the systemmay have pressure and vacuum holes spaced closer together (e.g., on amillimeter scale). The vacuum holes may hold the workpiece and reducethe deformation, and the pressure pads may keep the workpiece away fromthe supporting surface. The workpiece may not touch the support surface,and may be supported at a few μm (e.g., 1, 2, 10, 20, etc. μm) away fromthe support surface. This may allow the workpiece to more freely assumenatural shape in the plane of the workpiece. The vacuum arrangement ofFIG. 21, or an arrangement similar or substantially similar thereto maybe used in conjunction with each example embodiment described herein.

FIG. 10 illustrates a workpiece 1020 in a flat state, as may bepatterned in at least some example embodiments.

FIGS. 11A-11K illustrate a plurality of (e.g., eleven) differentpositions of a writing head in relation to the direction of the rotorscanner relative to the glass. The arrow in FIG. 11 represents thescanning direction.

FIGS. 11A-11C show dense matrices of pixels, for example, images of arectangular spatial light modulator with the rows and columns of thearray aligned with the sides of the rectangle. FIG. 11A illustrates anSLM in which a pixel grid is parallel, or substantially parallel, to thewriting direction. FIG. 11B illustrates an SLM pixel grid, which istilted relative to the writing direction. FIG. 11C illustrates an SLMpixel grid, which is tilted relative to the writing direction, the tiltin FIG. 11C being less than as compared to the tilt of the pixel gridaxis in FIG. 11B.

FIGS. 11D-11F show images of a dense matrix with the array rotatedrelative to the SLM sides, for example, by 0°, 45° and a third angle.The third angle may be an angle other than 0°, 45° or 90°. FIG. 11Dillustrates an SLM with a pixel grid slanted 45°with respect to thewriting direction. In example embodiments, the pixel grid may not beparallel with the edges of an outer edge of an SLM chip as in FIG.11A-11C.

In FIG. 11E the SLM chip is shown slanted such that one of the axes inthe pixel grid may be parallel, or substantially parallel, to thewriting direction.

In FIG. 11F the SLM chip may be slanted so that the neither the outeredge of the SLM chip nor any one of the pixel grid axis are parallel, orsubstantially parallel, to the writing direction. The axes of the sidesof the matrix of pixels (e.g., an SLM) and/or the axes of the pixel gridmay be rotated with respect to the axes of movement during writingand/or the axes of the written pattern, thus providing, at least foursets of coordinate directions as will be described below with regard toFIGS. 12B-12D.

FIG. 11G shows a relatively sparse matrix skewed or rotated so that therows fall at different positions during scanning. In exampleembodiments, the area may be filled in one or several scans. In FIG. 11Ga plurality of laser diodes (e.g., five lines and/or five rows) slantedto the writing direction.

FIG. 11H shows relatively a sparse row of pixels, for example, aplurality of (e.g., three) laser diodes may be arranged orthogonal tothe writing direction. If utilizing the example embodiment shown in FIG.11H, multiple passes may be required to fill a desired area.

FIG. 11I shows a relatively dense row of pixels, for example, an imageof a one-dimensional SLM in which a plurality of (e.g., seventeen) laserdiodes may orthogonal to the writing direction.

FIGS. 11J and 11K show single rows with the pixels displaced in thescanning direction. FIG. 11J illustrates a plurality of (e.g., twelve)laser diodes in a row slanted to the writing direction. FIG. 11Killustrates a line of a plurality of (e.g., seventeen) laser diodesslanted to the writing direction according to an example embodiment.

A common problem with optically written patterns, as well as withinkjet-printed ones is the formation of “Mura.” The formation of Murarefers to the formation of visible bands or patterns due to thevisibility of the fields or stripes and/or due to moire effects betweenthe pattern and the writing mechanism. “Mura” is an issue for imagedevices (displays and cameras) but not for other laser-written patternssuch as PCBs and PCB masks.

At least some example embodiments provide a method for assemblingoptical fields to a display pattern by repetition along an x and a yaxis. The fields may be, for example, SLM fields, an SLM pixel pattern,or an array of pixels formed by another writing mechanism such as anarray of diodes.

As discussed above with regard to FIG. 12A, the arrangement according tothe conventional art is used in higher-precision pattern generators andmay produce acceptable levels of “Mura” defects. However, exampleembodiments provide writing systems having 10, 100, or even 1,000 timeshigher throughput than conventional pattern generators, but withessentially the same or substantially the same “Mura” reductionrequirements. Higher speed, larger pixels, multiple writing units and/ormultiple writing heads, may contribute to more geometrical errors in thewritten pattern. As will be described in more detail with regard to FIG.12B-12D, the pattern and the axes of the writing head may be rotatedrelative to each other, such that a single pixel is not repeatedlyprinted on the edge of adjacent pixels. Furthermore, the axes betweenthe movement system and the pixel grid created by the writing units maybe rotated relative to each other. The pattern may be aligned with themovement axes, the pixel grid or neither. The rotation may be an angledifferent from 0, 45 and 90°.

As discussed above with regard to FIG. 12A, the rotation direction isparallel to a side of the SLM chip in the conventional art.

FIGS. 12B-12E show example embodiments, which may suppress theoccurrence of Mura and/or weaken the effects of Moire in the pattern. Asshown, in example embodiments, the pattern may be rotated relative tothe axes of the writing mechanism and/or the movement system (e.g.,scanning direction of the SLM).

For example purposes, FIGS. 12B-12E will be described with regard to anSLM pattern. However, similar principles apply to other exampleembodiments, such as, any suitable writing unit.

In FIG. 12B, the workpiece may be wrapped onto the workpiece holder, andmay not be in parallel with the central axis of the workpiece holder.The SLM, or more generally the writing unit, may be arranged in therotor scanner with an outer side of the SLM chip, or more generally theaxes between the pixels formed in the pattern by the writing unit, inparallel, or substantially parallel, with the scanning direction. Forexample, the scanning direction and the SLM field are aligned, while theworkpiece is rotated relative to the scanning direction and the sides ofthe SLM pattern. With this rotation of the workpiece, the effect of astitching artifact no longer accumulate along a single line of thedevice but will pass from line to line, spreading the disturbance tomany lines. In addition, a Moire pattern, which is really anintermodulation product between frequency components of the pattern andthe writing mechanism (e.g. display pixels and laser scanner pixels),may be relocated to a higher frequency that is less visible in thefinished display.

In FIG. 12C the SLM chip, or a similar pixel map formed by the writingunits, may be arranged in the rotor scanner with at least coordinateaxes non-parallel to the rotational direction. The workpieces may bearranged with an axis of symmetry in parallel to the central axis of theworkpiece holder.

In FIG. 12D all three coordinate systems are non-parallel to each other.Together with FIG. 11 it is possible to define four coordinate systems,which may be rotated relative to each other. Two, three or fourcoordinate systems may be made oblique relative to each other in orderto reduce “Mura” effects, while all four parallel defines the prior art.

In FIG. 12E, the workpiece is rotated, the writing SLM field is rotatedand intentional distortion is introduced.

An angle between the sides of the SLM pattern and the workpiece forreducing Mura effects may be greater than or equal to about 0.01 radians(e.g., between about 0.01 and about 0.05 radians, inclusive). The angleused, however, may depend on the write mechanism, scale and/or type ofthe pattern. The angle may be adjustable from one writing job to thenext, or on the other hand, fixed and built into the writing hardware.

FIGS. 24A-E illustrate methods for continuous scanning in the x and ydirections, according to an example embodiment.

FIG. 24A shows an array of pixels in the x-direction along the toolaxis. The array may move with a constant speed and after the cylinderrotates one turn, the array stitches to the printed pattern. If thearray is not sufficiently dense, the scanning speed may be reduced to,for example, half so that two turns are needed to move the width of thearray. The scanning speed may also be reduced more or less depending onthe density of the array. The array may be parallel or not parallel tothe tool axis.

FIG. 24B shows another method for patterning, according to an exampleembodiment, in which the array is not parallel to the tool axis.

In FIG. 24C, an array parallel to the y-axis of the workpiece andperpendicular to the tool axis. In this example embodiment, the surfaceof the workpiece is patterned by continuous scanning in the x and ydirections.

FIG. 24D shows an example embodiment in which an array is less densethen those illustrated in FIGS. 24A-24C. In this example, a second arrayis needed to fill voids in the less dense array. The second array may bea physical array or the same array in a later pass.

FIG. 24E shows two passes on top of each other. A first of the twopasses scans to the right, and a second of the two passes scans to theleft. The simultaneous scanning of x and y may provide an oblique angleand the two passes may have opposite angles. This may reduce visibilityof resultant stripes. The two passes may be written sequentially withthe same pixel array, or with two pixel arrays moving in oppositex-directions, for example, simultaneously. The two pixel arrays may betwo physical write heads arranged on two different toolbars. The systemshown in, for example, FIG. 25 with continuous scanning in x andreciprocating scanning in y may be used to write two passes in a singleoperation.

As described above, the oblique writing is possible and indeed naturalfor a writing system with cylindrical motion. However, oblique writingis also beneficial in flat-bed writers, such as will be described inmore detail below.

FIG. 22 illustrates a writing apparatus, according to another exampleembodiment. As shown, the writing apparatus may include a rotor scanner2200 for generating a pattern on a workpiece 2202. The exampleembodiment shown in FIG. 22 may be similar or substantially similar tothe example embodiment shown in, for example, FIGS. 1, 7A, 7B and/or 7C,however, the example embodiment shown in FIG. 22 may further include aworkpiece shape controller 2204. The workpiece shape controller 2204 mayscan in the same direction as the rotor scanner 2200. In at least oneexample embodiment, the workpiece shape controller may scan theworkpiece 2202 such that the workpiece shape controller 2204 and therotor scanner stay in constant horizontal alignment.

FIG. 15 is a perspective view of a writing apparatus, according toanother example embodiment. The rotor scanner of FIG. 15 may be used topattern a flat workpiece, such as the workpiece shown in FIG. 10.

Referring to FIG. 15, the rotor scanner 1520 may include a plurality ofoptical writing units (not shown) arranged on a flat portion (e.g., atop and/or bottom surface) of the rotor scanner 1520. The plurality ofoptical writing units may be arranged such that they emitelectromagnetic in an axial direction relative to the rotor scanner 150.In at least one example embodiment, the optical writing units may bearranged around the outer edge of the bottom of the rotor scanner 1520.As shown, the rotor scanner 1520 may rotate and/or move along thesurface of a workpiece 1510. The width of the rotor scanner 1520 maycover the width of the workpiece 1510. In example embodiments, the rotorscanner may scan the workpiece in a varying direction, and may form arelatively shallow and/or run across the workpiece at an angle such thatthe arc is not tangent to 0, 45 or 90 degrees. This geometry may be usedwith thicker and/or non-bendable masks.

FIG. 17 is a top view of writing apparatus shown in FIG. 15. Referringto FIG. 17, the diameter D of the rotor scanner 1520 is narrower thanthe width of the workpiece 1710. In example embodiments, the rotorscanner may track or scan back and forth over the workpiece 1710 so asto cover the entire workpiece 1710. In example embodiments, the rotorscanner 1520 may write continuously regardless of which direction therotor scanner is moving. In an alternative example embodiment, the rotorscanner may write in a single direction.

FIG. 18 is a top view of a portion of a writing apparatus, according toanother example embodiment. The example embodiment of FIG. 18 may besimilar or substantially similar to the example embodiment discussedabove with regard to FIG. 17, however, the example embodiment of FIG. 18may include at least two rotor scanners 1810 and 1815. In exampleembodiments, the rotor scanners 1810 and 1815 may pattern the sameworkpiece 1820, for example, simultaneously.

FIG. 19A illustrates a side view of a rotor scanner according to anexample embodiment, and FIG. 19B illustrates a top view of the rotorscanner shown in FIG. 19A. In the example embodiment shown in FIGS. 19Aand 19B, the diameter D of the rotor scanner 1520 is greater than thewidth of the workpiece. The rotor scanner of FIGS. 19A and 19B may tracklaser diodes at a side of a workpiece in parallel with the workpiecemotion. This tracking or scanning illustrated in FIGS. 19A and 19B mayresult in a higher dose at the sides of the workpiece than the dose inthe middle of the workpiece, given that the dose of the laser diodes isthe same. This may be compensated for by increasing the dose of thediodes and/or pixels when patterning the center part of the workpiece.

FIG. 16 is a perspective view of a writing apparatus, according toanother example embodiment.

Referring to FIG. 16, the writing apparatus may include a circular stage1630 on which a workpiece 1610 may be fixed. A writing head 1620 may bearranged so as to span at least the diameter of the circular stage 1630.The writing head 1620 may include a plurality of optical writing units(not shown) arranged on a surface portion of the writing head, such thatelectromagnetic radiation emitted by the optical writing heads impingeson the workpiece 1610 during writing. In example operation, the circularstage, and thus, the workpiece 1610 may rotate while the writing head1620 moves perpendicular to the rotational axis of the circular stage1610.

FIG. 23 is a more detailed illustration of the pattern generator shownin FIG. 16.

FIG. 20 illustrates a non-Cartesian coordinate system in a rotorscanner, according to an example embodiment. For example, the coordinatesystem may be bent. In this example, a memory mapping may be performedbefore, during or after patterning to transform pixels in the Cartesiangrid to pixels in the bent coordinate system defined by the rotatingpixels relative to the workpiece. For each circle created by a singlepixel in the writing head a transformation may be made from a Cartesiangrid into the bent coordinate system

FIGS. 25-28 illustrate flatbed platforms, according to exampleembodiments.

FIG. 25 illustrates a flatbed platform, according to an exampleembodiment. The platform shown in FIG. 25 may be a lightweight frame,shown for example purposes as a truss. However, example embodiments maybe built with thin walled tubes that may be temperature controlled byfluid (e.g., air, water and/or gas) flowing within the tubes. The framemay provide a more rigid support for a stationary stage top. Writingheads (e.g., mechanical units holding writing optics) may be arranged onmechanical support structures, herein referred to as tool bars, near thesurface of the workpiece. At least one toolbar may extend across thestage. Each of the toolbars may include one or more tools (e.g., writingheads). The tools may be mounted or arranged in a similar orsubstantially similar manner to that as described above with regard tothe cylindrical stage. The toolbars may have fixtures or tools (e.g.,which may be standardized). The number of toolbars and the toolsattached to each toolbar may be configured according to the applicationand/or need for capacity.

FIG. 25 shows how toolbars 2501 access any point on the workpiece 2503,and how the toolbars may be moved out of the way for loading andunloading. The platform of FIG. 25 may include a linear motor 2504 fordriving the toolbar assembly 2506. The linear motor may be attached to arod 2502 extending between supports 2508 and 2510 standing separately onthe floor. A freely moving counter mass (not shown) may be used so thatneither part of the linear motor is connected to the ground. The linearmotor may move the toolbar assembly 2506 and the counter mass byapplying a force there between, while keeping a common, stationarycenter of gravity.

A separate system including the motor applying a weak force between theground and the counter mass may keep the counter mass centered within arange of movement.

The moving stage may slide on bearings (e.g., air bearings) and may holdthe workpiece using, for example, vacuum, electrostatic force or anyother suitable clamping mechanism. The moving stage may more accuratelymonitor and/or control the position of the stage relative to thecoordinate system of the machine. The platform of FIG. 25 may besuitable for many processes, such as, metrology, patterning, etc.

FIG. 26 illustrates a flatbed platform, according to another exampleembodiment. The example embodiment shown in FIG. 26 may be similar orsubstantially similar to the flatbed platform of FIG. 25; however, theflatbed platform of FIG. 26 may include a different number of toolbars(e.g., five toolbars) mounted in a fixed position. In this exampleembodiment, the workpiece 2601 shuttles back and forth on a light-weightshuttle 2602.

Referring to FIG. 26, the stage may be relatively lightweight similar orsubstantially similar to the shape of the support. The stage may bedriven by linear motor and the reaction force from the motor is isolatedfrom the support of the stage either by separate connections to theground or by a counter mass. The stage may slide on bearings (e.g., airbearings) and may hold the workpiece using vacuum, electrostatic forceor any other suitable clamping mechanism.

FIG. 27 illustrates another example embodiment in which the workpiece2701 passes under the tool bars and may be patterned in passing. Theworkpiece may be in the form of cut sheets or a roll-to-roll endlessband. As discussed above, patterning may involve exposure ofphotoresist, patterning of thermally sensitive resists of films, anyphotoactivation of the surface, ablation, thermal transfer or anysimilar processes using reaction to photon energy and/or heat of a lightbeam. According to at least some example embodiments, light refers toany electromagnetic radiation with a wavelength from EUV (e.g., down to5 nm) to IR (e.g., up to 20 microns).

FIG. 28 shows an example operation of a flatbed platform forhigher-speed patterning of workpieces, according to an exampleembodiment. For example purposes, this example operation will bedescribed with regard to FIG. 26; however, other flatbed platforms,according to example embodiments, may operate in similar orsubstantially similar manners. The platform may have the same orsubstantially the same type of lightweight board frame and a floatinglightweight stage, hereinafter referred to as a “shuttle,” 2804.

Referring to FIG. 28, in example operation, the shuttle 2804 mayoscillate (e.g., bounce) between counter masses 2802 positioned at eachend of the support 2806. The counter masses 2802 may freely move betweenposition A and B via slides 2810, but may be affected by the force ofthe linear motor. When the shuttle 2804 impacts or hits against acounter mass 2802 the shuttle 2804 loses at least a portion of kineticenergy. The force during the impact may be controlled by springconstants of springs 2812 compressed during the impact. At an end ofeach stroke, the shuttle 2804 impacts the counter mass 2802. The countermasses 2802 may be joined by a fixed rod 2814 or controlled individuallyby one or more linear motors.

A linear motor may also be positioned, for example, under the shuttle2804 and may accelerate the shuttle 2804 toward a first impact when theshuttle 2804 begins moving. The liner motor may also be used to move andstop the shuttle at any position, and/or maintain a constant orsubstantially constant speed during scanning. The shuttle may operate ata constant speed, moving, for example, to the left or to the right inFIG. 28. The stiffness of the springs 2812 may be selected such that themaximum acceleration is within a desired range, such that the workpiecedoes not slide on the stage and such that excessive vibrations are notgenerated in the stage.

In at least some example embodiments, the stage may be comprised of, forexample, a leaf spring with pads floating on the support structure andother pads holding the workpiece. With a flexible light-weight shuttlethe shape of the stage may be determined by the shape of the supportingsurface.

FIG. 29 shows a diagram over the position of the stage and the countermasses during scanning. FIG. 29 also shows the position of the toolscanning at a constant speed in the direction perpendicular to thepaper. When the stage is scanning to the right an oblique line is tracedby the tool across the workpiece and after the bounce and other obliqueline is traced with a different angle. With the proper relation betweenthe tool width, the stage speed, and the tool speed two contiguouspasses may be written on top of each other. Both passes may have stripesinclined to the scanning axis of the stage which may reduce periodicdefects in a pattern as shown.

If the workpiece is about 2.8 m long, accelerating at about 10 g duringbounce, and moving at a constant speed of about 6 m/s otherwise, theaverage scanning speed including bounce-time is approximately 5 m/s.Momentum may be transferred between the counter masses 2802 and thestage, none of which are connected to the supporting structure or to thefloor. After the bounce counter mass 2802 recedes with a speedsignificantly lower than the stage, the linear motor may reduce thespeed and reverse the velocity of the counter mass until the next impactwith the same counter mass.

If the counter masses 2802 are connected by a rod, or alternatively, ifa single counter mass is arranged at the center of the stage is used,the demands on the linear motor may be reduced. In this example, bouncesat each end reverse the velocity of the counter mass(es), and themovement of the counter mass may be similar or substantially similar tothat of the stage, except slower and with less range.

In one or more example embodiments, patterns may be written onworkpieces (e.g., glass sheets, plastic sheets, etc.) used in, forexample, electronic display devices such as LCDs. In these exampleembodiments, a workpiece larger than about 1500 mm may be used. Anoptical writing head (e.g., a rotor scanner) with a plurality of writingunits (e.g., greater than or equal to 5) may be used. A data channelwith a data rate (e.g., greater than or equal to 100, 200, 400 Gbits/s,etc.) may provide data, and the workpiece and the optical writing head(or rotor scanner) may be rotated relative to one another in at leastone direction. The workpiece and the writing head may also be movedrelative to one another in a plane, for example, between 45 and 135degrees relative to the plane of rotation. For example, in at least oneexample embodiment, the plane of rotation may be perpendicular to theplane of movement.

Although example embodiments have been described with regard toworkpieces, it will be understood that workpieces may be usedinterchangeably with workpiece. In addition, writing apparatuses,according to example embodiments, may be used in conjunction withconventional pattern generation systems.

According to at least some example embodiments, the written pattern isnot sub-divided into stripes. In at least some example embodiments withnon-interfering pixels (e.g., FIG. 1 and FIGS. 11G-11K) an image may bebuilt from parallel lines extending from one side of the workpiece tothe other.

In some example embodiments, (e.g., FIG. 1), the lines may be writtenfrom edge to edge and in sequence by the writing units. Two adjacentlines may be written by two adjacent writing units thereby reducing(e.g., minimizing ) the risk of the workpiece and/or writing head movingby drift and/or mechanical movement from one line to the next. Thesequentially written edge-to-edge pattern local errors may be reducedand “Mura” effects may be reduced.

In an example embodiment similar to FIG. 1, but including more than onering of writing units (e.g., FIG. 7A) or with an arrangement of writingunits or non-interfering pixels as shown, for example, in FIG. 11G-11Kthe lines may not be sequentially written. However, with multiplewriting units distributed around the perimeter of the cylinder, twoadjacent lines may still be written by writing units in proximity to oneanother on the perimeter of the writing head (e.g., within 90° from eachother and in relatively close time proximity). In addition, multiplewriting units distributed around the perimeter of the cylinder may stilllimit the freedom for drift and/or vibration between the lines.

In example embodiments using SLMs to form simultaneously contiguousarrays of pixels (e.g., one-dimensional (1D or two-dimensional (2D))adjacent arrays may be written sequentially and/or in close proximity intime, thereby reducing the stitching areas between the pixel arrays (SLMstamps). Helical scanning with multiple writing units, together with thecalibration of writing units against the same calibration sensor, mayreduce mismatch between the images from the writing units, whether theimages are single points, clusters of non-interfering pixels or denseareas of pixels (SLM stamps).

As shown in FIG. 1B, lines traced by the writing units may be obliquerelative to the workpiece. This can be corrected if the workpiece isrotated on its support. However, as described above, obliqueness may beused to reduce “Mura” effects, and thus, an increase in the obliquenessof the traced lines may be desirable. A pixel pattern is defined by thescan lines and may be rotated relative to the axes of the pattern, forexample, the pixel pattern of the display devices.

A third coordinate system is defined by the movement of the writing headand the rotation/shuttle movement. If the oblique angle between thepixel grid is changed by rotation of the workpiece on the cylindricalsupport, all three coordinate systems are rotated relative to eachother. In other example embodiments only two of the three coordinatesystems are oblique to each other.

FIG. 1C illustrates images created by an SLM during scanning. As shown,the images in FIG. 1C are also rotated relative to the workpiece. Asdiscussed in relation to, for example, FIGS. 11A-11K and/or FIGS.12A-12E, in this example embodiment, four coordinate systems exist andtwo, three or all four may be rotated relative to each other to reduce“Mura” effects in the written pattern. Reduction of “mura” by rotationof the various coordinates systems may be used while scanning eithercylindrically or in a flat-bed stage. In the circular stages shown inFIG. 15 and/or FIG. 16 the coordinate system of the movements rotateduring the stroke from edge-to-edge thus creating a local butnon-constant rotation between the coordinate systems.

The helical scanning may be implemented by rotating the workpiece, thewriting head, or both, and the workpiece can be inside or outside of thewriting head.

While example embodiments have been described with reference to theexample embodiments illustrated in the drawings, it is understood thatthese example embodiments are intended in an illustrative rather than ina limiting sense. It is contemplated that modifications and combinationswill readily occur to those skilled in the art, which modifications andcombinations will be within the spirit of the present invention and thescope of the following claims.

1. A method for generating a pattern on a workpiece, the methodcomprising: scanning at least one optical writing unit across a surfaceof a workpiece creating a pixel grid, the pixel grid being arranged atan angle relative to axes of features of the pattern, the angle beingdifferent from 0, 45 or 90 degrees.
 2. The method of claim 1, whereinthe scanning creates at least two equidistant scan lines.
 3. The methodof claim 1, wherein the scanning is performed in at least twodirections.
 4. A writing apparatus for generating a pattern on aworkpiece, the apparatus comprising: a writing head including at leastone optical writing unit configured to scan across a surface of aworkpiece to create a pixel grid, the pixel grid being arranged at anangle relative to axes of features of the pattern, the angle beingdifferent from 0, 45 or 90 degrees.
 5. The apparatus of claim 4, whereinthe writing head is configured to create at least two equidistant scanlines during scanning.
 6. The apparatus of claim 4, wherein the writinghead is configured to scan the workpiece in at least two directions. 7.A method for generating a pattern on a workpiece, the method comprising:rotating a rotor scanner having a plurality of optical writing units,each of the optical writing units emitting electromagnetic radiation;and scanning, concurrently with the rotating of the rotor scanner, theworkpiece by moving at least one of the workpiece and the at least onewriting head in a direction perpendicular to a plane of rotation of therotor scanner.
 8. The method of claim 7, wherein the electromagneticradiation is emitted in a radial direction relative to the rotorscanner.
 9. The method of claim 7, wherein the electromagnetic radiationis emitted in an axial direction relative to the rotor scanner.
 10. Themethod of claim 7, wherein the scanning of the workpiece includes,scanning the workpiece in a first direction to create a pixel grid, thepixel grid being created at an angle relative to at least one of thefirst direction and axes of the pixel grid, the angle being differentfrom 0, 45 and 90 degrees.
 11. The method of claim 7, wherein thescanning of the workpiece includes, scanning in the workpiece in a firstdirection to create a helical pattern on the workpiece.
 12. The methodof claim 7, wherein the electromagnetic radiation is emitted in adirection parallel to at least one of a plane of rotation of the rotorscanner and the scanning direction of the rotor scanner.
 13. The methodof claim 7, wherein the pattern generated on the workpiece includes aplurality of equidistant scan lines.
 14. A writing apparatus forgenerating a pattern on a workpiece, the apparatus comprising: a rotorscanner including a plurality of optical writing units, each of theoptical writing units emitting electromagnetic radiation, the rotorscanner being configured to scan the workpiece by rotating the rotorscanner and moving at least one of the workpiece and the at least onewriting head in a direction perpendicular to a plane of rotation of therotor scanner.
 15. The apparatus of claim 14, wherein theelectromagnetic radiation is emitted in a radial direction relative tothe rotor scanner.
 16. The apparatus of claim 14, wherein theelectromagnetic radiation is emitted in an axial direction relative tothe rotor scanner.
 17. The apparatus of claim 14, wherein the rotorscanner creates a helical pattern on the workpiece during scanning. 18.The apparatus of claim 14, wherein the electromagnetic radiation isemitted in a direction parallel to at least one of a plane of rotationof the rotor scanner and the scanning direction of the rotor scanner.19. The apparatus of claim 14, wherein the pattern generated on theworkpiece includes a plurality of equidistant scan lines.
 20. A methodfor patterning a workpiece, the method comprising: scanning a pluralityof optical writing units across a surface of the workpiece, each of theplurality of optical writing units having a separate final lens; movingthe workpiece and the plurality of optical writing units relative toeach other, the relative motion being a combination of linear movementand circular motion in a direction perpendicular to the linear motion.